JERUSALEM, Jan 5 (Reuters) - People in Gaza were in dire need of food and medical supplies, aid agencies said on Monday, but Israel's ground assault and air raids were hampering relief efforts.

Freezing cold is compounding the misery of children caught in the conflict. And body bags for victims are in short supply.

"The situation in Gaza since the Israel Defense Forces launched their ground offensive on Saturday night has become both chaotic and extremely dangerous," the International Committee of the Red Cross said in a situation report.

Air raids had damaged hospitals, water supply systems, government buildings and mosques but it was difficult for ICRC staff to move around to assist, it said.

About 530 Palestinians have been killed, at least a quarter of them civilians, since Israel launched its offensive on Dec. 27 to curtail Hamas rocket attacks from Gaza.

Ground troops invaded the enclave, home to 1.5 million Palestinians, on Saturday night after a week of bombardments from the air and from naval vessels.

Hospitals were inundated with Palestinian wounded, the ICRC said. Fresh supplies were urgently needed, including painkillers and anaesthetics but also body bags and sheets to wrap corpses.